why is George in charge of Lennie

Lennie used to live with his aunt.Before the aunt died, she asked George to take care of Lennie (for obvious reasons!).

Just to add, the aunt's name was Clara and George was a childhood friend. Lennie is mentally slow and needs George to function through the social norms of the time.

George was in- from Mental Retardationcharge of Lennie because Lennie suffered